<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<ul class="el">
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
</ul>
<script src="http://lib.sinaapp.com/js/jquery/1.9.1/jquery-1.9.1.min.js"></script>
<script type="text/javascript">
    $(function () {
        document.w
        $(".el").children().each(function(index){
            console.log(index);
            if(index%2 == 0){
                $(this).hide(1000);
                $(this).css("background-color","#999");
                $(this).show(1000);
            }else{
                $(this).hide(1000);
                $(this).css("background-color","#666");
                $(this).show(1000);
            }
        });
    });
</script>
</body>
</html>